There are occasional efforts to make copyright laws match across countries, but (a) the motivations behind copyright in each country vary, and (b) the efforts are almost always driven by Big Media to maximize copyright (profit) globally.
Bottom line here, in the US the Sherlock Holmes stories are public domain. Sorta. Well, mostly. But possibly not entirely. Not for a while yet. Until things change again. Clear now?
Sherlock Holmes and the Case of the Public Domain
The Independent Filmmaker Project fosters the development, production and promotion of hundreds of feature and documentary films a year.
And that's why copyright lawyers make a bloody fortune.
NPR's On the Media covered copyright issues in their latest episode, "The Past, Present, and Future of Ownership." You can get the podcast here:
http://www.onthemedia.org/2013/mar/08/?utm_source=local&utm_media=treatment&utm_campaign=daMost&utm_content=damostviewed